1. Field of the Invention
This invention relates to an electrical device carried by a vehicle. The electrical device processes input signals representative of (1) the velocity of the vehicle, and (2) the distance from the vehicle to a stationary or moving object (including another vehicle), in order to obtain an output signal representative of the probability of a collision between the vehicle and the object. The invention also relates to a method by which the electrical device processes the velocity and distance input signals, in order to obtain an output signal representative of the probability of a collision between the vehicle and the object.
2. Description Of Related Art
A variety of systems have been proposed in recent years for warning the operator of a vehicle of a potential collision and, if necessary, triggering automatic safety devices such as airbags and extendable bumpers based on the probability that a collision will occur. Given a suitable "front end," i.e., a device for detecting and measuring the existence to a potential obstacle, this would appear to be a relatively trivial problem since the equations of motion which govern the dynamic behavior of moving objects has been known for centuries. However, the fact that a need for such systems still exists indicates that the problem is not trivial, despite the availability of inexpensive and reliable optical and radio frequency range finders suitable for use as front ends in a collision avoidance or warning system. While the equations of motion are well-known, the manner in which these equations have been applied has greatly varied, and always with disappointing results.
Prior collision avoidance or warning systems range from extremely sophisticated doppler and/or tracking radar systems and automatic pilots which use artificial intelligence to guide military attack aircraft over rough terrain at supersonic speeds, to systems which simply monitor the distance to an object and provide a warning when a threshold minimum distance is detected. The more sophisticated systems are at present too complex and costly for general purpose civilian applications, while simpler systems have heretofore provided too little meaningful information to be useful. Despite extensive research programs by automobile manufacturers and others, and the demonstrated capabilities of the more sophisticated collision avoidance systems, particularly in aircraft, none of the previously proposed systems has proven adequate for use in automobiles and other passenger vehicles.
In order to be useful, an automotive collision avoidance or warning system must be relatively inexpensive, and yet be capable of providing meaningful warnings in all situations which might be encountered by the operator of the vehicle, while minimizing the possibility of false alarms. No such system currently exists.